Operating near BEP: system curves decide real savings
Pump efficiency marketing is often quoted at best efficiency point, but plants frequently operate away from BEP due to control margins, throttling practices, or seasonal demand shifts. Efficiency programs should start with a system curve review: valve throttling losses, unnecessary bypass flows, and oversized impeller trimming opportunities.
Request suppliers to annotate expected operating region on the curve for each real case, not only the single BEP number.
VFDs: savings potential and new failure modes to manage
VFDs can save energy when demand varies, but they also introduce harmonics, bearing currents, and control complexity. Cable screens, drive filters, and earthing must be engineered as a system.
Define minimum speed limits to avoid unstable regions or excessive temperature rise in motors not designed for extended low-speed operation.
Maintenance state is an efficiency variable
Worn wear rings and damaged impellers move the operating point and increase power draw for the same apparent discharge performance. Efficiency audits should include mechanical wear assessments, not only electrical metering.
Implement simple KPI tracking: kWh per cubic meter moved for transfer duties, tracked monthly.